JUBA (Reuters) - Three U.S. aircraft came under fire from unidentified forces on Saturday while trying to evacuate Americans from a spiralling conflict in South Sudan. The U.S. military said four of its members were wounded in the attacks.

Nearly a week of fighting in South Sudan threatens to drag the world's newest country into a Dinka-Nuer ethnic civil war just two years after it won independence from Sudan with strong support from successive U.S. administrations.

The U.S. aircraft came under fire while approaching the evacuation site, the military's Africa Command said in a statement. "The aircraft diverted to an airfield outside the country and aborted the mission," it added.

The statement said all of the three Osprey CV-22 aircraft involved in the mission had been damaged.

Consequently, U.S. President Barack Obama warned that any move to take power by military means would lead to an end of U.S. and international community support for South Sudan.

The United Nations mission in South Sudan said one of four U.N. helicopters sent to Youai, in Jonglei state, had come under small-arms fire on Friday. No crew or passengers were harmed.

Hundreds of people have been killed in the fighting between Dinka loyalists of President Salva Kiir and Nuer supporters of former Vice-President Riek Machar, who was sacked in July and is accused by the government of trying to seize power.

Fighting has spread from the capital, Juba, to vital oilfields and the government said a senior army commander had defected to Machar in the oil-producing Unity State.

The German military said on Saturday it had evacuated 98 people, including Germans and other nationals, from South Sudan by air to neighbouring Uganda. The German ambassador to South Sudan was among them, the Foreign Ministry in Berlin said.

A separate plane took Lieutenant-General Hans-Werner Fritz, chief of Germany's Operations Command, along with his aides and five other Germans, to Berlin, the military said.

After meeting African mediators on Friday, Kiir's government said on its Twitter feed that it was willing to hold talks with any rebel group. The United States is sending an envoy to help find a negotiated solution.

South Sudan's foreign minister, Barnaba Marial Benjamin, told Reuters the government had given African mediators the go-ahead to meet Kiir's rivals, including Machar and his allies.

Ethiopia's Foreign Minister Tedros Adhanom, who led an East African delegation of foreign ministers in Juba aimed at mediating between the feuding sides, said the team did not manage to meet Riek Machar face to face, neither did they make phone contact.

"We are trying to contact them. We are hopeful of having both sides on the negotiating table within the space of 10 days," Tedros told Reuters.

In their meeting with Kiir, Tedros said they were also aiming to get humanitarian aid to afflicted populations unhindered.

CEASEFIRE CALL

Benjamin said Lieutenant-General Lazarus Sumbeiywo, sent to South Sudan by Kenyan President Uhuru Kenyatta, had stayed behind along with a Kenyan diplomat after the African mediators left on Saturday and would work on making contact with Machar.

Sumbeiywo was the chief mediator in the talks that led to the signing of the 2005 peace agreements with north Sudan.

"So on the side of the government ... we have established dialogue without any condition," Benjamin said. "All we say, we urge former Vice-President Riek Machar not to incite the people of South Sudan through ethnic configuration."

United Nations staff say hundreds of people have been killed across the country, which is the size of France, this week and that 40,000 civilians are sheltering at U.N. bases.

The United Nations said on Friday at least 11 Dinka civilians had been killed during an attack by about 2,000 armed youths from another ethnic group on a U.N. peacekeeping base in Jonglei state. Two Indian peacekeepers were also killed.

U.N. Secretary-General Ban Ki-moon condemned the attack and called on Kiir and Machar "to come to the table and find a political way out of this crisis".

"They're responsible to the people of South Sudan to end the crisis and find a political means of resolving their differences," Ban told a news conference in the Philippines.

The African Union called on Saturday for a Christmas ceasefire, and its chairwoman Nkosazana Dlamini-Zuma described the killings of civilians and U.N. peacekeepers as a war crime.

Reuters television footage showed several hundred government troops leaving Juba to deploy in Jonglei state.

Toby Lanzer, the U.N. Humanitarian Coordinator in South Sudan, said via Twitter that Bor, in Jonglei state, remained tense. "We've heard clashes & seen bodies in the streets. Civilians have left town to flee for their safety," he wrote.

Information Minister Michael Makuei told Reuters an army divisional commander in Unity State, John Koang, had defected and joined Machar, who had named him the governor of the state.

Jacob Dut, a political science lecturer at the University of Juba, said most army divisions had between 10,000 and 13,000 troops, although not all were fully manned.

"Division 4 (Koang's unit) is adjacent to the border with Sudan. That means there is more military hardware and that means that this defection is a big loss," Dut said.

(Additional reporting by George Obulutsa in Nairobi, Elias Biryabarema in Kampala, Aaron Maasho in Addis Ababa, Rosemarie Francisco in Manila; Phil Stewart and Ros Krasny in Honolulu; Missy Ryan in Washington and Andreas Kenner in Berlin; Editing by Alistair Lyon and Eric Walsh)

BENGHAZI, Libya (Reuters) - A suicide bomb attack at an army base outside Benghazi in eastern Libya killed at least six people and wounded up to 15 on Sunday, medical and security sources said.

The attacker blew himself up in a car in front of the base in Barsis, some 50 km (30 miles) outside Benghazi, a security source said.

All those killed were soldiers, medical sources said, but the security source said the attacker was among those killed.

The security situation has sharply deteriorated in Libya's second-largest city in the past few months where car bombs and assassinations of army and police officers happen regularly.

Most countries closed their consulates in Benghazi after a series of attacks and some foreign airlines have stopped flying there. The U.S. ambassador and three other Americans were killed in September 2012 during an Islamist assault on the consulate.

Separately, tribesmen in Jalo in the southeast brought the bodies of five soldiers to a local hospital, state news agency Lana said. The soldiers had been killed in clashes two days ago, the agency said without giving details.

Western diplomats worry the violence in Benghazi will spill over to the capital Tripoli which last month saw the worst fighting in months between militias.

Much of Libya's oil wealth is located in the east where many demand autonomy from the Tripoli government, adding to turmoil in the North African country.

The government of Prime Minister Ali Zeidan is struggling to control militias and tribesmen which helped topple Muammar Gaddafi in a NATO-backed uprising in 2011 but kept their guns.

Oil exports, Libya's lifeline, have fallen to 110,000 barrels a day, a fraction of the more than 1 million bpd in July as armed militias, tribesmen and minorities have seized oilfields and ports to press for political and financial demands.

Zeidan has warned the government will be unable to pay public salaries if the protests continue.

BERLIN/MOSCOW (Reuters) - Former oil tycoon Mikhail Khodorkovsky was reunited with family members in Berlin on Saturday, a day after he was released from a decade-long jail term during which he became one of Russian President Vladimir Putin's most prominent critics.

Khodorkovsky, 50, was released from a remote prison near the Arctic Circle on Friday after Putin pardoned him with the stroke of a pen. He immediately flew to Berlin, where he was joined by his relatives, including his elderly parents, Marina and Boris, on Saturday.

"My family is finally reunited and we're very, very happy to be together after the 10 years of separation," his son Pavel Khodorkovsky, who arrived from the United States, said outside the Adlon Hotel in the German capital.

"As you can imagine my father is going through a lot right now," he said.

Khodorkovsky, who had been in jail since his arrest in October 2003 on fraud and tax evasion charges, was convicted twice of financial crimes, to which he pleaded not guilty.

In an excerpt from the first on-camera comment to the media since his release, Khodorkovsky told Russian magazine The New Times in an interview that his family was allowed only a handful of overnight visits during the years he was in prison.

"There was an opportunity - three days, once per quarter, during four years out of the 10 - to spend nights in the visiting room," said Khodorkovsky, who looked composed and relaxed in a black turtleneck sweater.

Supporters say the former Yukos oil company chief was jailed to curb political challenges to Putin, bring his oil assets under state control and warn other tycoons to toe the line.

Yukos was bankrupted and sold off. Its main production asset now forms the core of state oil company Rosneft, which is headed by an influential Putin ally, Igor Sechin.

PUTIN'S DECISION

Putin's decision to pardon Khodorkovsky, who had been due to be released next August, was widely seen as an effort to improve Russia's image before it hosts the Winter Olympics in February in the Black Sea resort city of Sochi.

The pardon sent Russian share prices upward briefly but economists said real reforms to Russia's economy and its justice system would be needed to remove the discount its stocks sell at compared to other emerging markets.

Putin said on Thursday that Khodorkovsky sought a pardon because his mother was ill, and his spokesman said the request meant Khodorkovsky had admitted guilt. Khodorkovsky said in a statement on Friday that although he had asked Putin for a pardon for unspecified family reasons, he did not admit guilt.

Russian media have speculated that fears of new charges that could have threatened to keep him in jail past next August could have influenced his decision to seek a pardon.

Putin's spokesman has said Khodorkovsky is free to return to Russia.

The United States and European Union welcomed Khodorkovsky's release but made clear they want to see Russia make sustained efforts to strengthen rule of law and respect for human rights.

"Putin is making efforts to revamp the battered façade of his authoritarian Russia," said German opposition Greens' politician Marieluise Beck, who met Khodorkovsky on Saturday.

His release "cannot blind us to the fact that Russia is just as far away from being a state governed by the rule of law as it was before this pardon," she said in a statement.

(Writing by Steve Gutterman; Editing by Sonya Hepinstall)

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